A disc is disposed between vertebrae. Also, the outside of the disc is protected by tough fibers, and vertebral pulp exists inside the disc.
Discs function as joints and play very important roles for minimizing an impact applied to vertebrae while vertebral pulp changes in position and shape according to movement of the vertebrae. The vertebral pulp is mostly moisture (water). When we get older, an amount of moisture gradually decreases, and thus, a buffer function of a disc is lost. As a result, when an excessive pressure is applied to the fibers, backache may occur. Here, if the excessive pressure is continuously applied, the fibers may be seriously stretched or ruptured to push nerve roots placed at a rear side thereof, thereby causing pains of pelvis, legs, and the like. Thereafter, a distance between the vertebrae gradually decreases, or the vertebrae are collapsed to cause various kinds of side effects such as vertebral deformation.
There is a method, in which an intervertebral fusion device, so-called, a cage is inserted between two adjacent vertebrae after a disc between the damaged vertebrae is removed, as a method for treating diseases involved due to the disc. That is, the cage recovers the distance between the vertebrae to its original distance between the two adjacent vertebrae, which corresponds to an original height of the disc, thereby recovering the vertebral function.
The surgical method in which the cage is inserted between the vertebrae includes an anterior lumbar interbody fusion (ALIF) method in which a cage is inserted from a front side of a vertebra after an abdominal operation, a lateral lumber interbody fusion (LLIF) method in which a cage is inserted through a side portion, a transforaminal lumbar interbody fusion (TLIF) method in which a cage is inserted in a diagonal direction at a point that is spaced a distance of 30 mm to 40 mm laterally from a center of a back side, and a posterior lumbar interbody fusion (PLIF) method in which a cage is inserted from a back side.
According to the conventional TLIF surgical procedure, one side surface of the cage is inserted and located between the vertebrae in the diagonal direction through the back of the human body, and then, a front surface of the inserted cage is disposed to face the abdomen of the human body, thereby completing the insertion of the cage. An impactor that is an assisting mechanism for allowing the front surface of the cage to face the abdomen of the human body is needed. Here, force is applied to the other surface of the cage by using the impactor to rotate the cage so that the cage faces the abdomen of the human body.
In case of the conventional TLIF surgical procedure, the position of the cage is easily influenced by the skill level of an operator, and it is difficult to accurately locate the cage between the vertebrae. Thus, when the cage is not accurately located between the vertebrae, surgical operation effects may be deteriorated.